Experimental Colonic Carcinoma production will be continued employing Methylnitronitrosoguanidine (MNNG) and Dimethylhydrazine (DMH). Our previous studies whick indicate that it is possible to prepare antisera which react with murine tumor-associated antigens will be extended. If confirmed, the antigens will be characterized and purified by standard methods such as Gel Filtration, Electrofocusing, Acrylamide Gel Electrophoresis, and Affinity Chromatography. Radioimmunoassays will be developed for the antigens. Experiments will be done to determine if the type of antigen induced is related to the carcinogen used or if different carcinogens induce the same antigen. The Radioimmunoassays will be used to measure the antigen in tumors and plasma of experimental animals to determine if production or dissemination of antigen correlates with tumor growth as measured by the double contrast Barium Enema technique recently developed in this laboratory. Fluorescein labelled antitumor antisera will be used in immunohistochemical studies of the rat colonic mucosa at various stages of tumor induction, and for cellular and subcellular localization of the tumor associated antigens. The effect of dietary supplementation with cholic and chenodeoxycholic acid on the rate of tumor appearance and rate of growth as judged by double-contrast Barium Enema will be studied. BIBLIOGRAPHIC REFERENCES: Gluckman, J., Skucas, J., Narisawa, T. and Turner, M.D.: Radiographic Demonstration of Rat Colonic Tumors (Abstract). Gastroenterology 68:901 (1975). Skucas, J., Gluckman, J.B., Fowler, E.H., Turner, M.D., and Narisawa, T.: Radiological Evaluation of Growth Characteristics of Rat Colonic Tumors (Abstract). Investigative Radiology ll: 372 (1976).